The Shah's regime was authoritarian, in the mold of most monarchies, but not especially repressive. In fact, the reason for the Khomeini revolution was that the Shah was considered inadequately pious, as demonstrated by his emancipation of women and institution of economic reforms. True, he did have a security police apparatus, the SAVAK, but given that the regime was threatened by internal and external agencies (Iraq had been a major problem, and Iran's location on the border of the Soviet Union made them a target of Russian expansionist goals), it's not like it wasn't needed.

Besides, the reason that the Shah lost power in the first place was that Carter refused to allow him to crush Khomeini's revolution, which was well within his capabilities. Carter, being a liberal, heard the word "revolution" and swooned. The Shah was driven out and Carter, against the advice of the CIA, admitted him to the US for medical treatment. Think about that. Carter allowed the Shah to be overthrown when he was a staunch ally ruling a nation that was strategically critical to us, but then, when he was no longer in a position to do us any good in the world, he welcomed him to the US, guaranteeing that the new regime would be enraged and alienated. If Carter had been hired by the Soviets to undermine our interests in the Middle East, he couldn't have done more damage than he did through his imbecilic bumbling. That he continues to rear his head and speak out against his successors, in view of his spectacularly failed leadership, is astonishing.